128440405 has 4 divisors (see below), whose sum is σ = 154128492. Its totient is φ = 102752320.

The previous prime is 128440397. The next prime is 128440427. The reversal of 128440405 is 504044821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 98922916 + 29517489 = 9946^2 + 5433^2 .

It is not a de Polignac number, because 128440405 - 2³ = 128440397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12844036 + ... + 12844045.

It is an arithmetic number, because the mean of its divisors is an integer number (38532123).

Almost surely, 2^128440405 is an apocalyptic number.

It is an amenable number.

128440405 is a deficient number, since it is larger than the sum of its proper divisors (25688087).

128440405 is an equidigital number, since it uses as much as digits as its factorization.

128440405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25688086.

The product of its (nonzero) digits is 5120, while the sum is 28.

The square root of 128440405 is about 11333.1551211479. The cubic root of 128440405 is about 504.5457536700.

The spelling of 128440405 in words is "one hundred twenty-eight million, four hundred forty thousand, four hundred five".